Method and device for the subjective determination of aberrations of higher order

ABSTRACT

A device for the subjective determination of aberrations of higher orders Xi in an optical system, in particular in an eye includes at least one observation channel into which defined plates can be introduced, the individual plates having optically active structures which correspond to a defined Zernike polynomial and to a defined amplitude, at least one order Xi of the Zemike polynomial being greater than two.

BACKGROUND

The present invention relates to a method and a device for thesubjective determination of aberrations of higher order in an opticalsystem, in particular in an eye.

In order to improve the quality of optical systems such as imagingsystems and laser irradiation, optical wavefronts of these systems areanalysed. In the article “Objective measurement of wave alternations ofthe human eye with the use of a Hartmann-Shack wave front sensor” byLiang et al, Optical Society of America 1994, p. 1949 ff., it isdescribed how, with Shack-Hartmann sensors, aberrations of higher ordercan be recorded and evaluated in the form of Zernike coefficients of thevarious orders.

This objective determination of the Zernike coefficients results in animprovement in quality of the system. However, this objectiveimprovement in quality displays differences from the subjectivelyevaluated visual power of this optical system.

This fact has been taken into account for the conventionalspherocylindrical correction of refractive errors of the human eye inthat the ophthalmologist objectively establishes the correction valuesby means of refractometers and then, in order to provide the subjectivefine adjustment for the patient, determines the final data by means oftest spectacles or a phoropter and a reading chart. For higheraberrations (starting from the 3^(rd) order), these subjective tests endmerely in a straight decision that the correction does or does notachieve certain effects. However, a subjective fine adjustment is notpossible.

Beyond the normal spherical and cylindrical correction of aberrations,in order to correct higher aberrations as well, adaptive lenses can beused in theory which operate as deformable mirrors in reflection orliquid crystal lenses in transmission. Despite intense efforts, however,these adaptive lenses cannot yet be used industrially due to theirsensitivity.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method and a devicefor the subjective determination of aberrations of higher orders in anoptical system, with which a subjective fine adjustment is easilypossible.

The present invention provides a device for a subjective determinationof aberrations of higher orders in an optical system. The deviceincludes an observation channel and a plurality of individual platesconfigured to be introduced into the observation channel. Each plate hasoptically active structures corresponding to a defined Zernikepolynomial and to a defined amplitude of the defined Zernike polynomial.The defined Zemike has an order greater than two.

In particular, the present invention provides a device for thesubjective determination of aberrations of higher order Xi in an opticalsystem, in particular in an eye, comprising at least one observationchannel into which defined plates can be introduced, the individualplates having optically active structures which correspond to a definedZemike polynomial and a defined amplitude, at least one Zernikepolynomial having an order greater than two.

Such an optical system can be for example an eye, in particular a humaneye. The optical system can also be an optical instrument for examiningthe ocular fundus (retina) in which the aberration of higher order ofthe specially examined eye is compensated. Furthermore, it is possibleto understand as an optical system optical instruments such astelescopic sights or eyepieces of the microscope together with the eyelooking through these. In addition, an optical system can be abeam-guiding system such as a laser or laser diodes in which aberrationsof higher orders are to be corrected.

The observation channel is a defined path in which correction elements,in particular plates, can be introduced. This observation channel can bea free space, a vacuum or also a (partially) transmitting medium, suchas air, gas or liquid. The observation channel is particularlypreferably a tube which protects the area surrounding it from externalinfluences such as atmospheric fluctuations, dust, etc.

Aberrations of higher orders Xi in an optical system are aberrationswhich occur as wavefront aberrations and can thus be formulatedmathematically in the most varied manner. The aberrations areparticularly preferably described here by Zernike polynomials. Theadvantage of this description is firstly the orthogonality and secondlyeach polynomial stands for a known aberration in the lens (astigmatism,coma, etc.). The wavefront aberration W(p,θ) is therefore described bythe overlaying of the individual polynomials Zn (p,θ).

${W\left( {p,\theta} \right)} = {\sum\limits_{k = 0}^{n}{k_{n}{Z_{n}\left( {p,\theta} \right)}}}$

This property is exploited in the present invention by using aphase-plate set for each term knZn (p,θ) of the sum.

Starting from these properties of the Zernike polynomials, theorthogonality and the description of an optical image error, in thepresent invention the aberrations are preferably determined andcorrected independently of each other. To this end, in each case a setof phase plates P^(m) is preferably used, which correspond to a Zernikepolynomial Wz (p,θ) and are classified in terms of their coefficientk_(z) (the amplitude of the wavefront portion). The classification iscarried out such that each amplitude can be set quasi-continuously viacombinations. For the present invention, such a set of phase plates ispreferably used for each Zernike polynomial—and therefore for eachimaging or image error.

In addition to image errors as parameters, a phase-plate set has theoptical zone as a characterizing variable in which the wavefrontcorrection is carried out. This can also be universally varied and set.

The individual plates have optically active structures which correspondto a defined Zernike polynomial and to a defined amplitude, i.e. to adefined polynomial coefficient k_(z). Thus an optically active structurewhich precisely corrects this aberration can be applied to a plate for aspecial Zernike coefficient, i.e. for a special coefficient of a specialZernike polynomial. The optically active structure which is applied tothe individual plates then also differs with regard to a speciallydefined Zernike polynomial from other plates with this optically activestructure by different defined amplitudes or polynomial coefficients.For example, a set of plates which corrects the individual aberration toa varying intensity results from a sensibly selected series of differentamplitude strengths for the same Zernike polynomial.

Particularly preferably, several aberrations of various terms of Zernikepolynomials can also be combined on one plate. Thus it is conceivable tocombine all 4^(th)-order errors in one plate or else to realizeindividual terms of the Zernike polynomials with different coefficientson one plate (for example an X1 coefficient k1 with term X2 andcoefficient k2=2×k1).

As a result of this, a device is provided in which an aberration ofhigher order in the corresponding optical system can be corrected bysimple introduction of a correspondingly defined plate. By combiningseveral plates which are introduced one behind the other into theobservation channel, the sum of the aberrations of the errors correctedby the individual plates can be established or compensated by theaddition of the Zernike polynomials.

In a preferred embodiment of the present invention, a device with aplate set of plates is provided which has optically active structures tocompensate aberrations of at least one defined Zernike polynomial. As aresult of this, it is possible to provide a plate set for a specialaberration, corresponding to a Zernike polynomial, in which each plateof this set corrects a special aberration. Thus, for example a set cancomprise plates to compensate aberrations of a third-order Zernikepolynomial and to compensate aberrations of a fourth-order Zernikepolynomial. It is also possible for aberrations of Zernike polynomialsof lower order, for example second order, to be corrected by furtherplates. By adding different plates, a more complex aberration, or thewhole wavefront, can then be calculated or compensated.

In a further embodiment of the present invention, a device is providedin which a plate set has a subset of plates which has individual plateswith optically active structures to compensate aberrations of variousamplitudes for a defined Zernike polynomial. As a result it is possible,in the case of an aberration which corresponds to a Zernike polynomial,to provide a subset of different plates which also compensate theaberration of this Zernike polynomial, but with different amplitudes orcoefficients. With the help of such a subset of plates, it is possibleto delimit and particularly finely adjust the aberration with regard tothe Xn polynomial by optional, iterative or alternating use of thedifferent plates of the subset. Particularly preferably, the individualplates of a subset are sorted and combined in a classified manner, sothat the individual plates are arranged according to their amplitudes.The aberration can thus be delimited very accurately both by selectingone of the plates of the subset and combining different plates of thesame subset. In addition, it is possible to correct the entireaberration of different higher orders Xi in the optical system by addingdifferent plates from different subsets.

A plate set and/or a subset of plates is particularly preferablyarranged on a circular disc. This circular disc is particularlypreferably located in a device which is developed as a phoropter. As aresult, it is possible to resort to proven mechanical structures inorder to determine and to compensate errors of the third and higherorder in a novel way.

In a particularly preferred version of the present invention, a targetapparatus for the patient's view is additionally provided. In this way,it is possible to satisfy strict requirements in respect of thealignment of the individual plates relative to the optical axis, forexample of the eye which looks through. The inlet and outlet aperture ofthe phase-plate phoropter can be used as a target apparatus. This can becentred for example so that the visual axis of the eye coincides withthe optical axis of the phase-plate phoropter.

The plates are particularly preferably made of glass or plastic. Theypreferably consist of a transmitting plastic. The plates are preferablymade by means of spot-scanning excimer lasers by ablation of thinplastic or special-glass plates. The plates are particularly preferablymade of PMMA. Other transparent materials that are easily processable bymeans of lasers are also particularly preferably used. The processinglaser advantageously has a Gaussian beam profile. Furthermore,processing machines of the optical industry that are directed to precisepoints can be used to produce the thin glass plates with ahigh-precision surface polishing quality, for example by “single pointdiamond turning technology”. Crystals are also preferably used here.

The device according to the invention is particularly preferably usedfor the subjectively evaluated establishment of the aberration of higherorder within the framework of the determination of visual acuity. Thisis a sight test which precedes for example a correction using readingaids or a laser. In this way, the aberrations detected for example byobjective wavefront aberration can again be subjectively finely adjustedand can thus be used to increase the quality of the objectivelyestablished theoretical output data.

The device according to the invention is also preferably used tooptimize the resolution of optical instruments, such as for exampleduring examinations of the ocular fundus (retina) by compensating theaberrations of higher order of the special eye. During this observationof the rear section of the eye for medical purposes, the aberration ofthe eye to be examined plays a not insignificant role in thishigh-precision and high-resolution observation, as it limits theresolution of the area to be examined. In order to compensate theaberration of this eye for observations with a fundus camera or similar,the device according to the invention can be used and a set of phaseplatelets that fully compensate the aberration can be introduced intothe beam path. The best possible observation and resolution and optimumoptical quality is therefore possible. It is particularly advantageousin the case of this use that the aberrations can be rapidly compensateduniversally for different eyes by preferably setting the phoropter phaseplates to a known value.

The device according to the invention is particularly preferably used tocorrect beam profiles of beam sources, in particular of laser diodes.The forming of wavefronts which emerge from beam sources is a task whichis often set. There are above all two requirements here. Firstly, theprovision of ideal wavefront profiles (flat wave/pure Gauss profile) andsecondly the intentional deformation or intentional forming of wavefrontprofiles. The use of the present invention in laser diodes is to benamed here as an example. For a broad application, the correction orfine correction of the established wavefront profile is necessary. Tothis end, the wavefront aberration is conventionally recorded andcorrected by means of phase plates of the present invention. As aresult, it is possible to create one and the same wavefront profile witheach laser diode which can vary substantially in its wavefrontaberrations. This is easily and universally possible by means of thepresent invention. This approach therefore differs greatly from theproduction of a correction plate for a particular laser diode for aparticular optical application. In the absence of the laser diode, thecorrection plate can no longer be used and a new correction plate mustbe produced for the new laser source. This can be universally solvedwhen using the present invention as the new radiation source can thenalso be individually corrected with the device according to theinvention.

A further advantageous use of the device according to the inventionrelates to the individual correction of vision defects, in particularwhen using optical instruments. When using optical instruments, anincrease in quality can result from the correction of aberrations ofhigher order, in particular those caused by vision defects, by using thedevice according to the invention. This can be used for example in thehunter's telescopic sight or in the eyepiece of the microscope. It ispossible here to obtain optimum resolution by individual subjectivedetermination of the aberrations. Not only a defect-free, but even asuperproportional visual acuity which goes beyond full visual power canbe achieved here.

The object of the present invention is also achieved in particular by amethod for the subjective determination of an aberration of a specialhigher order x in an optical system, in particular an eye, in which in afirst step a plate is introduced into an observation channel of theoptical system, the plate having optically active structures whichcorrespond to a defined Zernike polynomial and to a defined amplitude,the order x of the Zernike polynomial being greater than 2, in a secondstep a subjective assessment of the current wave deformation of thedefined order x is carried out and in a third step comprising therepeated application of the first step with plates of differentamplitude correction of the same defined Zernike polynomial and of thesecond step of the subjective determination, the plate and therefore theamplitude correction is established which subjectively best compensatesthis aberration of the special higher order x. This method can be usediteratively or alternately and thus leads to a minimum of deviation. Dueto this universal possibility of analyzing wavefront profiles, these canbe compensated on the basis of a target value. The wavefront profile canbe iteratively established by the modular principle and guided to aminimum of deviation.

In a particularly preferred method of the present invention, thepreviously described method is carried out successively for each of theoccurring aberrations of different orders X1-Xn. The addition of thecorrections for the individual polynomial coefficients produces thetotal correction of the aberrations of the optical system.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be explained further in the following withreference to the drawings, in which:

FIG. 1: a plate set for the 3^(rd)-degree coma image errors in the xaxis and 3^(rd)-order spherical aberration, each with a subset forpolynomial coefficients from 0.5 to 10;

FIG. 2: an arrangement of circular discs with subsets of platesaccording to the present invention, each arranged in a circular disc;

FIG. 3: an arrangement of a device according to the invention during theexamination of an eye by means of a fundus camera;

FIG. 4: a schematic representation of the use of the device according tothe invention for the correction of the beam profile in laser diodes;and

FIG. 5: an arrangement of a device according to the invention in aconjugated image plane.

DETAILED DESCRIPTION

A plate set for 3^(rd)-degree coma image errors of the x axis and3^(rd)-order spherical aberration, each with a subset for polynomialcoefficients from 0.5 to 10, is schematically represented in FIG. 1. Theplate set for 3^(rd)-degree coma image errors in the x axis according tothe formula W(p,θ)=(3p²−2p) sin(θ) is designated A and the sub-plate setfor the image error of the 3^(rd)-order spherical aberration accordingto the formula W(p,θ)=6p⁴−6p²+1 is designated B. These two subsets A andB together form the plate set according to FIG. 1. Subsets A and B eachconsist of five individual plates which are laid out within the definedZernike polynomial for different polynomial coefficients, i.e.amplitudes. Thus subset A has individual plates for polynomialcoefficients 0.5, 1.0, 2.5, 5 and 10. Subset B also consists of fiveplates with different polynomial coefficients 0.5, 1.0, 2.5, 5 and 10.With this plate set, consisting of subsets A and B, image errors canthen be determined and compensated according to the two addressedZernike polynomials. These aberrations of higher orders in these opticalsystems can be established and compensated in a targeted manner with thehelp of this ordered selection of phase plates by establishing in atargeted manner wavefronts which are deformed as desired and of whichthe spherical and cylindrical parts have previously been corrected withstandard lenses, and by correcting the individual ordersquasi-continuously and orthogonally. This takes place through a kind ofmodular principle with which a universal establishment and correction ofany wave profiles can be carried out. Image errors of optical systemscan thus be minimized and therefore maximum imaging quality can beachieved. In this way, a universal possibility is provided to analyzewavefront profiles and to compensate them on the basis of a targetvalue. Through the modular principle, the wavefront profile isiteratively established and guided to a minimum of deviation. The plateset ideally consists of further subsets C, D . . . (not represented) inorder to be able to compensate the desired image errors according tofurther Zernike polynomials.

An arrangement of circular discs with subsets of plates according to thepresent invention arranged, each in a circular disc, is schematicallyrepresented in FIG. 2. A plate set 25 is represented here withindividual subsets 26.1 to 26.6 of a plate set, wherein, within theindividual subsets 26 for one special Zernike polynomial in each case,plates of different amplitudes of this Zernike polynomial are providedin a classified manner, each in a circular disc. The circular disc 12.1is represented particularly enlarged, on which plates 26.1.1 to 26.1.5are represented which compensate the aberration of different amplitudesof a particular Zernike polynomial. In addition to these, an opening26.1.0 has been left free—this corresponds to the amplitude 0 for thisZernike polynomial, i.e. indeed no correction of the correspondingaberration in error-free optical systems. In addition, an observationchannel 15 is schematically represented by a straight line. Through thisobservation channel 15, an eye 5 can see centrally through a recess ineach circular disc. The sum of the plates, swivelled in the observationchannel, of the subsets 26 arranged on the individual circular discs 12then have an effect on the eye.

In order to then establish the aberrations, all the circular discs 26.1to 26.6 are aligned such that the plate with amplitude 0 of all thecircular discs comes to rest in the observation channel 15, i.e. in theend that no compensations take place. One circular disc after the otheris then further swivelled such that the person looking through theobservation channel 15 can subjectively determine whether there is animprovement due to the individual plates of the subset and when this isat its most optimal. Once the optimum compensation of the individualplate of a subset is found, the next circular disc is swivelled orintroduced into the observation channel 15 and thus the plates of thenext subset are offered, until the optimum is also calculated for thisaberration. After all six subsets are set via the circular discs suchthat in each case the plate with the optimal compensation is swivelledin the observation channel 15, the sum of the individual plates, whichcompensates the entire wavefront deformation optimally according to theperson's subjective impression, has an effect on the eye 5.

With these transparent thin-glass or plastic plates and the thus-orderednumber of phase plates in a circular disc which are classified in termsof their classification according to the order of the Zernikecoefficients and the respective amplitude, these plates are incorporatedin a defined manner into the mechanical system for example of aphoropter in which plates of an order of the Zernike coefficients with adifferent amplitude have preferably been arranged in a circular disc.Through centred arrangement of such circular discs one behind the other,it is possible to swivel optionally phase plates of a different order ofthe Zernike coefficients and of a different amplitude into an opticalaxis with a target apparatus. Thus, on this optical axis with target orcentering apparatuses, every combination of aberrations of higher ordercan be corrected quasi-continuously for the eye or optical system to becorrected.

A particular advantage of this version lies in the comparatively robustreproducible design in which the lateral spatial resolution of the phaseplates is determined by the production technology and can be in thesubmillimetre range. The additive structure of the Zernike polynomialsallows an additive compensation of any wavefront deformation through toan ideal, desired wavefront (flat wave, etc.). A proven mechanicalsystem is resorted to by the use of the phoropter principle for phaseplates of a different strength of the respective aberration of higherorder. Such a phase-plate phoropter particularly preferably has exactlycentred phase plates which have with regard to position and angledeviation of less than 0.1 mm, or 0.1 degrees (dx, dy<0.1 mm; dv<0.1°),as well as particularly preferably a target apparatus for the patient'sview. As a result of this, a subjective establishment of the value ofthe aberration of higher orders is possible within the framework of asight test (determination of visual acuity) before a correction usingvision aids or lasers. Furthermore, it is possible to optimize theresolution of optical moments when examining the ocular fundus (retina)by compensating the aberrations of higher order of the special eye.Furthermore, the aberrations of higher orders of any optical systems canbe established and compensated with the help of a device according tothe invention.

The procedure for the determination of an aberration of the human eyeusing the present invention is typically as follows: a phase plateletP_(n) ^(m) of a phase set P^(m) is swivelled in front of the opticalsystem of the eye. The eye and the optical axis of the phase plateletsare overlaid by an optical target and centering apparatus. It istherefore guaranteed that the optical centres of the eye and of thephase platelets lie on top of each other. Thereafter the amplitude ofthis phase set is increased (by swivelling the next platelet P₊₁ ^(m) ofthe phase set P^(m)). This takes place iteratively, or alternately untilthe patient's subjectively firm image impression is found. Once this hastaken place, the image error of the phase plate P^(m) is described andguided to a subjective minimum.

In the next step, the above-described procedure is continued with thefollowing set P^(m+1) of phase plates which describe a further imageerror to be corrected. All previously found phase platelets

P_(1 …  n)^(1 …  m)of the optimal correction remain swivelled. Through this procedure, thepatient is led step-by-step to an optimum—i.e. to the minimization ofall the image errors.

The classification of the phase platelets is such that all the possibleamplitudes can be set in a sensible range. The statistical occurrence ofthe aberrations in the optical systems or patients is used here astarting point. Particularly preferably, these curves are developedequidistant between a maximum and minimum value.

The lower limit of the wavefront amplitude is determined by the Rayleighcriterion from which it can be deduced that only wavefront differencesof greater than λ/4 have a significant effect on the image quality. As aresult, it is possible to determine subjectively the aberration of theeye in the case of wavefront deformations of higher orders, the naturallight spectrum being able to be used simultaneously. This is notpossible in the case of the known aberrometers for the determination ofthe wavefront deformation of higher order, as these requiremonochromatic light.

A further advantageous application of the present invention will beexplained with reference to FIG. 3. An arrangement of a device accordingto the invention for the examination of an eye by means of a funduscamera is schematically represented in FIG. 3. A camera 6 or amicroscope or a slit lamp is represented here which can observe an eye 5via an observation channel 15 (represented as an idealized optical axisin the form of a straight line). Phase plates 20.1 to 20.3 areintroduced in the observation channel 15 between the eye 5 and thecamera 6. The wavefront W1, which emerges from the eye 5, is deformed byaberrations due to the suboptimal optical system of the eye. This issymbolized by a corresponding wave-shaped representation of thewavefront W1. Upon passing through the phase plates 20.1 to 20.3, theseerrors of higher order are compensated so that the emerging wavefront W2no longer has these aberration errors and therefore these deformations,and strikes the camera 6 as a flat wave.

As a result of this, an application in ophthalmology is opened up by anembodiment of the present invention, in which the rear section of theeye is observed. This serves for medical observations. For thishigh-precision and high-resolution observation, the aberration of theeye to be examined plays a not insignificant role, as it limits theresolution of the area to be examined. In order to compensate theaberrations of this eye for observation with a fundus camera or similar,a set of phase platelets which fully compensate the aberration isintroduced into the beam path. Thus the best possible observation andresolution is possible with optimum optical quality.

A further area of application is schematically represented in FIG. 4.The use of a device according to the invention for the correction of thebeam profile in laser diodes is shown schematically here. A laser diode7 serves as a beam source and emits beams along an observation channellying in the optical axis (schematically represented by a straight line15). The beams emerging at the laser diode 7 are spherocylindricallycorrected (not represented) and strike phase plates 20.1 to 20.3 aswavefront W 1 with aberrations of higher orders. Here the beam profileis corrected such that it emerges as corrected beam profile W2 and has adesired wavefront W2. The forming of this wavefront from beam sourcescan be desired as a flat wave or as a pure Gaussian profile. Intentionaldeformation is involved here, or intentional forming of wavefrontprofiles. This is very easily and universally possible using a device ofthe present invention. A very fine correction of the establishedwavefront profile can thus be carried out for correspondingapplications.

The wavefront aberrations are conventionally recorded and corrected bymeans of phase plates of the present invention. It is therefore possibleto produce one and the same wave profile for each laser diode whichvaries greatly in its wavefront aberrations. The present inventiontherefore also differs greatly from the production of a correction platefor a particular laser diode for a particular optical application. Inthe absence of the laser diode or if the optical application is changed,this integral correction plate must be completely replaced. When usingthe present invention, the correspondingly corrected beam profile can besubsequently corrected or aligned for new applications. It is thereforepossible to convert any forming of the wavefront profiles of beamsources by the universal use of the present invention.

The phase plates 20 can also be arranged in a conjugated image plane forexample in the phase phoropter 2 according to FIG. 5. The observationchannel 15 is arranged offset relative to the eye 5, for example roughlyopposite the not directly examined eye. The beam path of the observationchannel 15 is reflected into the eye 5 via an optical-square arrangementconsisting of a first mirror 27 a and a second mirror 27 b, this canalso be for example a prism arrangement or the like. The first mirror 27a can be designed semipermeable, so that a further device 29 can bearranged in the beam path 28 of the eye 5. This can be for example adevice for the targeted stimulation of the eye 5.

With the present invention, a method of a device for the subjectivedetermination of aberrations of higher order is provided, with which itis possible to compensate in a target-oriented manner aberrations ofhigher order with the help of an ordered selection of phase plates. Anywavefronts, which were previously corrected conventionally by sphericaland cylindrical lenses or else corrected with integrated compensation ofaberrations of higher orders of the form of aspherical orders, arrangedin a targeted manner according to the amplitudes in the individualorders, can therefore be corrected quasi-continuously. The use ofsensitive adaptive lenses can be dispensed with and it is made possibleto reproducibly and quasi-continuously establish and compensate opticalaberrations of higher order, in particular in ophthalmology, with acomparatively robust instrument.

1. A method for the subjective determination of an aberration of aspecial higher order X in an optical system, comprising: in a firststep, introducing a first plate into an observation channel of theoptical system, the plate having optically active structurescorresponding to a defined Zernike polynomial having an order X and to adefined amplitude of the defined Zernike polynomial, the order X beinggreater than 2; in a second step, subjectively assessing a current wavedeformation of the order X; and in a third step repeating the first stepwith a second plate of different amplitude correction of the definedZernike polynomial and repeating the second step of the subjectivedetermination so as to select one of the first and second plates thatsubjectively best compensates the aberration of the special higher orderX.
 2. The method as recited in claim 1, wherein the optical systemincludes an eye.
 3. A method for the subjective determination ofaberrations of special higher orders X1 to Xn in an optical system,comprising: in a first step, introducing a first plate into anobservation channel of the optical system, the plate having opticallyactive structures corresponding to a defined Zernike polynomial havingan order X1 and to a defined amplitude of the defined Zernikepolynomial, the order X1 being greater than 2; in a second step,subjectively assessing a current wave deformation of the order X1; andin a third step repeating the first step with a second plate ofdifferent amplitude correction of the defined Zernike polynomial aridrepeating the second step of the subjective determination so as toselect one of the first and second plates that subjectively bestcompensates the aberration of the special higher order X1 in a fourthstep, successively repeating the first and second steps for each definedZernike polynomial having an order Xn, wherein Xn is greater than X1. 4.The method as recited in claim 3, wherein the optical system includes aneye.